Glaucoma is the second most common cause of blindness in the United States, affecting over 3 million Americans. It is actually a group of eye disorders that damage the optic nerve. The optic nerve is composed of many nerve fibers which normally send signals from the retina to the brain. In a normal eye, there is a clear fluid called aqueous humor which is produced and circulated in the front portion of the eye. To maintain a healthy amount of aqueous and normal eye pressure, your eye keeps a steady production of aqueous humor while an equal amount of aqueous humor flows out of the eye.
With glaucoma, the aqueous humor builds up in the eye and presses on the optic nerve, causing damage to the nerve fibers which shuttle information to the brain. When damage occurs to the optic nerve fibers, blind spots develop. These blind spots can go undetected until there is significant damage to the optic nerve. Glaucoma can cause blindness if untreated. Only about fifty percent of Americans who have glaucoma are even aware they have glaucoma. Glaucoma usually does not produce any early symptoms, and the disease usually progresses slowly.
Early detection and treatment of glaucoma can help preserve vision. Different types of glaucoma can include primary open-angle glaucoma, angle-closure glaucoma, normal-tension glaucoma and other types of glaucoma. Treatment depends on the specific type of glaucoma. Options can include topical medications, laser surgery, or outpatient surgery. Wichita Vision Institute offers a variety of diagnostic tests for glaucoma detection. Dr. Reena Patel provides a comprehensive glaucoma evaluation and will personally discuss potential treatment options if necessary.
About Glaucoma – Causes, Symptoms, and Diagnosis
In most cases of glaucoma, the optic nerve suffers injury from increased pressure in the eye. Healthy eyes are filled with a clear fluid (called aqueous humor) that leaves the eye through the anterior chamber angle, a channel located in the front of the eye. When something blocks the fluid from leaving the eye, pressure builds in the eye, and when it reaches a certain point, the pressure damages the optic nerve.
There are several types of glaucoma; the two most common are open-angle glaucoma and closed-angle glaucoma. Chronic open-angle glaucoma is the most common form of glaucoma in the United States. The exact cause of open-angle glaucoma is unknown, but it tends to run in families. Typically, someone with early open-angle glaucoma has no symptoms and their vision remains normal. As the drainage channel becomes less efficient at draining aqueous from the eye, the intraocular pressure increases. The increased intraocular pressure then damages the optic nerve which causes blank spots to form in the field of vision. These spots can become larger as optic nerve damage progresses and can result in blindness if all the optic nerve fibers are damaged.
Closed-angle glaucoma comes on quickly when the exit of the aqueous humor fluid is suddenly blocked, causing severe pressure, vision loss, and pain. Risk factors for closed-angle glaucoma include age, farsightedness (hyperopia), and Asian heritage. Symptoms of closed-angle glaucoma may include blurred vision, severe eye pain, headache, nausea and vomiting, or rainbow-like halos around lights. People who are at risk for developing closed-angle glaucoma should undergo preventative laser iridotomy treatment. Many common medications used to treat common conditions such as colds, insomnia, urinary incontinence, and other medications should be avoided until after laser iridotomy can be performed.
The most important risk factors for glaucoma include:
- elevated eye pressure (intraocular pressure)
- family history of glaucoma
- farsightedness or nearsightedness
- past eye injuries
- African, Spanish, Asian ancestry
- thinner central corneal thickness
- diabetes, migraine headaches, poor circulation
Glaucoma can be detected during a dilated eye exam, which is recommended for all adults before they turn 40, or sooner if there are risk factors for an eye disease. African-Americans and individuals with a family history of open-angle glaucoma should have regular dilated eye exams. Glaucoma screening that only checks the pressure of the eye is not adequate to determine glaucoma status. The only way to detect glaucoma is to have a complete dilated eye exam.
During your glaucoma evaluation, Dr. Reena Patel will look at multiple measurements such as tonometry, gonioscopy, ophthalmoscopy, perimetry, and optical coherence tomography. Tonometry is performed to check the intraocular pressure of the eye. Gonioscopy is a procedure that allows Dr. Patel to inspect the drainage angle of your eye and to determine whether an angle is open, closed, or narrow. Ophthalmoscopy allows assessment of the retina and optic nerve. Perimetry or visual field testing measures the peripheral vision of each eye. Optic nerve head ocular coherence tomography measures changes in the optic nerve fibers. Fundus photography may also be needed to document optic nerves. After analyzing these measurements, Dr. Patel will weigh all of these factors before deciding whether glaucoma treatment is needed or whether the need to be monitored closely as a glaucoma suspect is necessary.
Once damage has been caused by glaucoma, it cannot be reversed. Open-angle glaucoma can be treated with eye drops, oral medications, laser therapy, or surgery to decrease the eye pressure to prevent further damage. Closed-angle glaucoma can be treated with laser iridotomy. Periodic eye examinations are very important to assess whether the glaucoma is progressing and to potentially adjust treatment if necessary.
First-line glaucoma treatment includes eye drops or laser therapy. Glaucoma eye drops lower eye pressure by decreasing the amount of aqueous humor produced in the eye or by increasing outflow of aqueous humor through the drainage angle. Glaucoma eye drops can help preserve vision but can be expensive, are usually taken for life, and may also produce unwanted side effects.
Glaucoma eye drops may cause:
- blurred vision
- redness of the eyes or redness of the eyelids &/or skin surrounding the eyes
- dry mouth
- altered taste sensation
- change in eye color
- change in pulse or heart rate/chest pain
- changes in breathing/wheezing/gasping
- stinging/burning/itching sensation
- depression/changes in energy level
- numbness/tingling of hands & feet
- longer eyelashes
- kidney stones
- weight gain
Selective Laser Trabeculoplasty
Laser surgery may be recommended for different kinds of glaucoma. In open-angle glaucoma, the drainage angle is not as efficient draining aqueous humor from the eye. The increased pressure slowly and painlessly destroys optic nerve fibers. The drainage angle can be modified by a laser treatment called selective laser trabeculoplasty (SLT) to help control eye pressure.
Laser surgery can help reduce the amount of medication needed to control intraocular pressure. Also, if you have difficulty inserting eye drops, are not able to afford glaucoma eye drops, or do not use eye drops on a regular basis, selective laser trabeculoplasty can be used as a first-line treatment or in addition to taking medications.
Selective laser trabeculoplasty is an advancement over other glaucoma laser procedures which have been done for over two decades. SLT uses a neodymium:YAG laser to focus a low amount of light energy on the drainage angle of the eye. SLT targets only the pigmented cells of the eye in the drainage angle and has no effect on the surrounding tissue. Using a low amount of energy, the laser stimulates the healing response of the body to modify the drainage angle to lower eye pressure.
SLT is performed at Wichita Vision Institute by Dr. Reena Patel. The laser takes less than 10 minutes to perform. Initially anesthetic eye drops are placed in the eye. Glaucoma medication is also given to control intraocular pressure immediately after the procedure. There is rarely any discomfort associated with the procedure. After the procedure, your intraocular pressure will be monitored for the next one to two hours. Very rarely, eye pressure may elevate requiring further treatment. Vision may also be blurred the day of laser treatment and mild inflammation may occur.
Selective laser trabeculoplasty does take several weeks to months for the treatment to take full effect. SLT improves aqueous humor outflow without causing damage and successfully decreases eye pressure over 80% of the time. Over time, intraocular pressure may increase after SLT. Up to half of people treated with SLT may experience increased intraocular pressure five years after surgery. Dr. Patel can monitor your intraocular pressure and can repeat SLT laser treatment if necessary.
Laser Peripheral Iridotomy
In closed-angle glaucoma, the drainage angle becomes partially or totally blocked when the iris (the colored part of the eye) is over the angle. The iris can completely block the aqueous fluid from leaving the eye. Think of the eye as a sink with the faucet on, and the iris acts like a stopper in the sink. When this situation occurs, the intraocular pressure can increase very quickly and cause an acute-angle-closure glaucoma attack.
Patients with acute angle-closure glaucoma need immediate treatment to prevent blindness. Dr. Patel can perform a laser peripheral iridotomy, which uses a neodymium:YAG laser to open a new pathway in the iris (the colored part of the eye) and relieve pressure. The new drainage pathway allows the iris to fall back to its normal position and allows fluid to circulate freely within the eye, minimizing the risk of a rise in eye pressure. The iridotomy will not restore or improve vision but rather prevent further vision loss.
The procedure is performed in our office and is very quick, lasting just a few minutes. Anesthetic numbing eye drops are placed in the eye and glaucoma medication is also given to control intraocular pressure. There is mild discomfort associated with the procedure. Your intraocular pressure will be monitored for some time after the procedure. Complications following laser peripheral iridotomy are uncommon but include blurred vision, headache, inflammation, cataract, light streak or image, a spike in intraocular pressure, pain, and/or the need for re-treatment. Supplemental medications are usually prescribed to prevent post-operative inflammation and another rise in eye pressure.
If your glaucoma cannot be controlled by medications or laser treatment, you may need surgery to lower your intraocular pressure. There are multiple surgical procedures that can be performed to try to lower intraocular pressure. Recently, many new glaucoma devices have been approved to help lower intraocular pressure.